1. Technical Field
The present invention relates to a liquid ejecting head. More particularly, the present invention relates to a liquid ejecting head and a liquid ejecting apparatus which are capable of ejecting liquid from a nozzle opening using a piezoelectric element that includes a first electrode, a piezoelectric body layer and a second electrode.
2. Related Art
Piezoelectric elements that are typically used as pressure generating units for ejecting liquid from a nozzle opening of an ink jet recording head are usually formed by interposing a dielectric film formed of a piezoelectric material, which exhibits an electromechanical conversion function, between two electrodes. In some instances, the dielectric film is comprised of crystallized piezoelectric ceramics. In the process of forming the piezoelectric element, after a lower electrode film is formed on one face of a substrate where a series of flow paths are formed using a sputtering method, or the like. Then, a piezoelectric body layer (dielectric film) is formed on the lower electrode film using a sol-gel method, an MOD method, or the like. An upper electrode film is then formed on the piezoelectric body layer using a sputtering method or the like. Finally, a patterning process is performed on the piezoelectric body layer and the upper electrode film, and the piezoelectric element is formed. An example of this formation method is described in Japanese Patent Application JP-A-2001-274472.
In such piezoelectric elements, when a voltage is applied, stress is applied to the piezoelectric body layer. One problem with this configuration is that this stress may cause cracks to form in the piezoelectric body layer. This is particularly troublesome, when the piezoelectric body layer is a thin film and the stress applied to the piezoelectric body layer is increased. In addition, when a path of a leakage current flowing or leakage path is formed between two electrodes in the piezoelectric body layer, the insulation of the electrodes is degraded, and accordingly, there is a problem that the piezoelectric element generates heat and is destroyed so as to be degraded.
Such a problem is not limited to piezoelectric elements that are used in an ink jet recording heads but also exists in piezoelectric elements that are used in other liquid ejecting heads that are capable of ejecting other types of liquids. In addition, the above-described problem exits in a piezoelectric elements that are used in devices other than liquid ejecting heads.